Stock and recuitment

Question 1

What does the Ricker Stock-Recruitment graph show?

Answer 1

At low levels of parental stock, survival rate is at maximum.
As parental stock increases, mortality increases (density dependent factors).

Question 2

What does the Beverton-Holt Stock-Recruitment graph show?

Answer 2

At low levels of parental stock, survival rate is at maximum.
As parental stock increases, mortality levels off.

Question 3

What is
replacement
line?

Answer 3

The number of
recruits needed to
replace the deaths
among adults.

Question 4

How does better habitat affect the stock-recruitment curve?

Answer 4

1. Better habitat will increase recruitment. Conversely, worse habitat lessens the number of offspring per parent.
2. Better habitat means that the recruitment needed to replace stock would go down.
3. Better habitat will result in higher surplus production

Question 5

In constant catch:

Answer 5

a consistent level of fishing is allowed based on a single value, regardless of the stock status

Question 6

In constant fishing mortality:

Answer 6

There’s consistent biomass and abundance. Based on mortality rates

Question 7

In constant escapement:

Answer 7

A constant number of fish are allowed to escape the hatchery. Consistent spawn rates. Maximizes yield and minimizes risk.